It is well understood that in regard to today's economy, as well as in regard to environmental concerns, minimizing exhaust emissions, especially in internal combustion engines in automobiles, is critical. Many, if not all states in the U.S. have laws that regulate the amount of exhaust emissions that are allowed to be released into the atmosphere. These laws have led to significantly reducing the amounts of carbon monoxide, hydrocarbons, oxides of nitrogen, and other pollutants that have been released into the atmosphere on a per-automobile basis since the 1960's, when rising environmental awareness lead to the passing of the exhaust monitoring laws. Some states have also enacted statewide vehicle safety inspections which require the vehicle exhaust systems to be in sound condition with no major defects or leaks from any of the components. Consequently, automobile owners have a vested interest in keeping their cars maintained for peak performance. Failing an emissions control test, or any other safety inspection, means that the car owner must get the car repaired within a reasonable period of time, or potentially face fines and/or loss of vehicle registration. Further, it is well known that for most vehicles, a well maintained and well-tuned engine that produces small amounts of exhaust emissions maximizes performance including, among other factors, fuel economy. Fuel economy or lack thereof, is also a very important factor in automobile ownership for at least the past 30-40 years.
There are at least several reasons to maintain the integrity of the exhaust system. Exhaust system integrity is important to properly maintain catalytic converter efficiency, as well as the safety aspect to deliver the harmful exhaust gases rearward of the passenger compartment. Gaseous pollutants can be inadvertently released into the atmosphere if exhaust integrity is compromised. Reduced exhaust system pressure, i.e., reduced “back pressure,” can decrease the efficient operation of the automobile emission control system by not allowing certain types of emission controlling devices to operate, as well as allowing monitored gases to escape into the atmosphere before being converted by the catalytic converter Further, releasing pollutants prior to, or even after the catalytic converter, as a result of exhaust leaks, can have significant consequences, such as carbon monoxide poisoning of the driver and/or occupants of the vehicle.
Thus, there has developed over time the need to maintain the integrity of exhaust systems of internal combustion vehicles, and a means to verify the integrity of the exhaust system.
FIG. 1 illustrates a typical internal combustion engine 110 and exhaust system 125 that are commonly used by automobiles (autos) today (while reference is made to an auto, those of skill in the art can appreciate that this is merely one example of use by a device of an internal combustion engine, and many other devices utilize an exhaust system (e.g., construction equipment, forklifts, trucks, railroad and aircraft engines, among others, but in fulfillment of the dual purposes of clarity and brevity, discussion of any of the other examples has been omitted). As those of ordinary skill in the art can readily appreciate, FIG. 1 is a greatly simplified illustration. Engine 110 includes intake manifold 106, located on engine block 102, and to which is attached a means for introducing fuel (commonly gasoline, but which can include any other fuel such as propane, hydrogen, diesel, natural gas, among others) and air into engine 110 for combustion. The means for introducing fuel commonly used today includes fuel injection systems and carburetors 104. Fan 108, along with a radiator (not shown) provides means for cooling engine 110, and can also be considered part of engine assembly 110.
Following introduction of the fuel and air mixture, and internal combustion thereof, extremely hot exhaust gases 124 are emitted from engine 110 via exhaust manifold 112, and exhaust manifold pipe 114. Exhaust system 125 includes exhaust manifold 112, exhaust manifold pipe 114, catalytic converter 116, linking exhaust pipe 118, muffler 120, and exhaust pipe 122. This is a very generic picture, as many exhaust configurations can include two manifold pipes 114a,b, two mufflers 120a,b, two exhaust pipes 122a,b, among other differences. Further, it is possible that other exhaust configurations can omit a catalytic converter 116 and/or muffler 120. Exhaust gases 124 flow through exhaust manifold pipe 114 into catalytic converter 116, and then into linking exhaust pipe 118, which connects the output of catalytic converter 116 to the input of muffler 120. Attached to the output of muffler 120 is exhaust pipe 122, which is what is commonly seen protruding from the rear of autos. Exhaust gas 124 is released into the atmosphere from exhaust pipe 122.
As those of skill in the art can appreciate, in some configurations, exhaust manifold 112 can incorporate the catalyst in place of, or in addition to, it being part of catalytic converter 116. This is but one such example of the numerous variations that can exist in the design and manufacture of exhaust reduction devices. As such, the figures are not meant to be limiting, but only describe in a general fashion so as to render the embodiments easier to understand; those of skill in the art can appreciate that variations from manufacturer to manufacturer exist, and are all are considered to be within the scope of the embodiments discussed herein. As will be apparent, the invention can be used with any exhaust system
Sources of leaks can commonly occur at the joints between exhaust system components, and along rusted or cracked sections of exhaust pipe(s) 122 and/or muffler(s) 120. For example, when installing exhaust manifold pipe 114 onto exhaust manifold 112, each cylinder of engine 110 typically has its own exit point into exhaust manifold 112. Even on turbo-charged engines there are many connection points for exiting exhaust gasses, all of which require system integrity. Gaskets or machined clearances that allow metal-to-metal fit without the use of sealing gaskets can also be a source of exhaust gas leaks. In short, any means for inadvertent leakage of gases can be determined by exhaust system verification tester 300, as described in greater detail below.
As shown in FIG. 1, exhaust manifold 112 has four separate tubes that extend from a main portion and that are attached to exhaust pipe 114, typically with bolts/studs and machine thread nuts, and heat resistant and pressure resistant gaskets. Over time, these gaskets can degrade and fail, and become a well-known source of leaks of exhaust gas 124. These gaskets are typically used between each of the main components of exhaust system 125. For example, gaskets can be used between exhaust pipe 114 and catalytic converter 116, between catalytic converter 116 and linking exhaust pipe 118, and so on. On a typical internal combustion, or more generally, combustion vehicle there is a combination of bolted connections that contain gaskets, metal-to-metal flanges, and “slip fit” overlapping connections that require U-shaped exhaust claps (U-bolt clamps). Still further, due to very low clearances on some automobiles, and rather intricate undercarriage designs, each exhaust pipe itself can have several components, each of which may need to be joined together, again through use of the heat resistant and pressure resistant gaskets or U-bolt type clamps. For example, exhaust manifold pipe 114 can have two or even three separate components, each of which would need to be joined together with nuts and bolts, and the heat and pressure resistant gaskets.
Another source of leaks in exhaust system 125 is the metal pipes themselves. Over time, because the metal is exposed to very high temperatures, corrosive exhaust gases 124 and external chemicals such as oxygen, road salt (e.g., NaCl, CaCl, and MgCl), among others, exhaust system pipes 118, 122 will begin to rust and leaks will occur. On occasion, because of the intricate exhaust system design, the leaks can occur in areas that are not at all visible and can only be determined by feeling or listening for an exhaust gas leak. As those of skill in the art can appreciate, and discussed in greater detail below, feeling and/or listening for very hot exhaust gases is at least often less than pleasant, and can be at times dangerous.
FIG. 2 illustrates a typical automotive repair shop exhaust system verification or testing setup. Most, if not all, auto repair service centers and emission testing centers perform some sort of exhaust verification service. Exhaust verification service involves checking the integrity of exhaust system 125 in order to determine if there are any leaks, and if so, where the leaks are located. Leaks in an exhaust system, as discussed above, can lead to poor or lowered performance, failed emissions tests, and/or dangerous conditions wherein carbon monoxide and/or other pollutants produced by internal combustion engines can find their way into the passenger compartment of auto 200. The latter situation can have dramatic consequences, even leading up to death by carbon monoxide poisoning or accidents due to drivers impaired from carbon monoxide poisoning.
As shown in FIG. 2, auto repair shops will put auto 200 onto lift 204, or drive over a pit to access the undercarriage and mechanic 206 will start engine 110, while putting an exhaust gas tube 208 over exhaust pipe 122 to route exhaust gases 124 directly outside or through an exhaust gas evacuation system (not shown), so that dangerous levels of carbon monoxide and/or other pollutants do not build up in the service area. Exhaust gases 124 are then released in the atmosphere.
The mechanic 206 then tests exhaust system 125 of auto 200. The mechanic 206 will generally visually inspect exhaust system 125, looking for obvious leaks, as exhaust leaks can have a distinctive sound or smell, but sometimes exhaust gases 124 are colorless. In the latter case, mechanic 206 has no other choice than to listen carefully over the length of exhaust system 125 for leaks. Typically, a leak will manifest itself as a low rumble that must be heard over the sound of engine 110, as well as other shop noises which can be a very noisy environment. As those of ordinary skill in the art can further appreciate, exhaust systems 125 are typically “capped” off by hand during examination. As those of skill in the art can appreciate, “capping” exhaust system 125 means putting some obstruction in the end of the tail pipe by mechanic 206, and listening for leaks. If exhaust system 125 were capped on a weak but functional exhaust system, engine assembly 110 could build enough pressure to blow out a weak connection on muffler 120 or pipe(s) 118, 122. Or, in the process of capping exhaust pipe 122, mechanic 206 could be exposed to dangerously hot components and gases 124, and can be burned. Therefore, a low pressure “exhaust integrity” tester according to embodiments is needed.
But, even if no noises are heard, as is sometimes the case, mechanic 206 must then make what is referred to as a hand inspection. That is, mechanic 206 runs his hands over portions of exhaust system 125, especially the parts that cannot be seen, or which are very close to the noisy engine 110, and feel for a leak from exhaust system 125. Another method for determining the integrity of exhaust system's 125 components is to squeeze exhaust pipes 118, 122, usually with pliers, wrenches, or other tools. However, this practice has recently come under increased scrutiny. Increasing numbers of states and/or other jurisdictions are introducing legislation that does not allow the practice of squeezing an exhaust pipe with a large pair of pliers in an attempt to check the integrity of exhaust system components. It is alleged that the practice of squeezing exhaust system components can lead to collapsed pipes and/or exhaust system or other system's components and sometimes can create a new leak or may enlarge an existing leak.
In common practice, mechanic 206 will have an assistant put their hand over exhaust pipe 122 while the engine is running so that leaks of exhaust gases 124 can be located. This practice also requires internal combustion engine 110 to be running while the test is performed and therefore spews exhaust gases 124 into the air the whole time auto 200 is lifted in the air, a process known by those of skill in the art as a “running engine leak test.” Additionally, this practice not only jeopardizes the safety of the assistant but also puts mechanic 206 at risk for severe burns due to hot exhaust gases 124 and endangers mechanic 206 due to having his or her hands near moving components of a hot and running engine 110. Exhaust gases 124 are very hot, typically between 500° F. and 2000° F. with pipe temperatures near the engine in excess of 600° F., and as such, mechanic 206 must exercise extreme care to avoid being burned. Depending on where the leak is encountered (e.g., near exhaust manifold 114) performing a running engine leak test is not possible. This means mechanics 206 generally do the manual inspection as quickly as possible. Less conscientious mechanics 206 will tend to “gloss” over this portion of the test, and the result can be false positives, meaning that leaks can go undetected. As can be easily imagined, this can lead to more expensive repairs later, or repeated trips to the same or different automotive repair shops to correct the situation, which of course wastes the time and money of the owner of auto 200 and shop owners/mechanics.